Showing papers on "Sodium sulfide published in 2019"

Photocatalytic Hydrogen Production: Role of Sacrificial Reagents on the Activity of Oxide, Carbon, and Sulfide Catalysts

Abstract: Photocatalytic water splitting is a sustainable technology for the production of clean fuel in terms of hydrogen (H2). In the present study, hydrogen (H2) production efficiency of three promising photocatalysts (titania (TiO2-P25), graphitic carbon nitride (g-C3N4), and cadmium sulfide (CdS)) was evaluated in detail using various sacrificial agents. The effect of most commonly used sacrificial agents in the recent years, such as methanol, ethanol, isopropanol, ethylene glycol, glycerol, lactic acid, glucose, sodium sulfide, sodium sulfite, sodium sulfide/sodium sulfite mixture, and triethanolamine, were evaluated on TiO2-P25, g-C3N4, and CdS. H2 production experiments were carried out under simulated solar light irradiation in an immersion type photo-reactor. All the experiments were performed without any noble metal co-catalyst. Moreover, photolysis experiments were executed to study the H2 generation in the absence of a catalyst. The results were discussed specifically in terms of chemical reactions, pH of the reaction medium, hydroxyl groups, alpha hydrogen, and carbon chain length of sacrificial agents. The results revealed that glucose and glycerol are the most suitable sacrificial agents for an oxide photocatalyst. Triethanolamine is the ideal sacrificial agent for carbon and sulfide photocatalyst. A remarkable amount of H2 was produced from the photolysis of sodium sulfide and sodium sulfide/sodium sulfite mixture without any photocatalyst. The findings of this study would be highly beneficial for the selection of sacrificial agents for a particular photocatalyst.

Tin nanoparticles embedded in a carbon buffer layer as preferential nucleation sites for stable sodium metal anodes

Abstract: Sodium (Na) metal is one of the most appealing anode materials for grid-scale energy storage systems owing to the high earth abundance and low cost of Na resources. Nevertheless, the implementation of the Na metal anode is hindered by two primary issues associated with Na dendrite growth and volume expansion, resulting in low coulombic efficiency and poor cycle life. Herein we present a facile and scalable method to synthesize tin (Sn) nanoparticles (NPs) that are uniformly embedded within a carbon network (denoted as Sn@C composite), which can address the two issues simultaneously. Specifically, Sn NPs can serve as preferential nucleation sites to guide Na nucleation and thereby lower the Na deposition overpotential, while the carbon network can act as a buffer layer to effectively minimize the volume change and alleviate the exfoliation of Sn NPs over repeated cycles. Consequently, high-capacity Na anodes can be realized with long-term reversibility and stability. Moreover, a room-temperature Na–sulfur battery based on the Sn@C composite as an anode coupled with commercial sodium sulfide as a cathode was demonstrated to have significantly improved electrochemical performance. We believe that this work provides a new pathway for designing high-energy Na metal batteries.

One‐Pot Synthesis of Sulfur and Nitrogen Co‐Functionalized Graphene Material using Deep Eutectic Solvents for Supercapacitors

Abstract: A green approach to the synthesis of sulfur and nitrogen co-functionalized reduced graphene oxide (SN-rGO) is presented; it involves the reduction of graphene oxide (GO) using a deep eutectic solvent (DES) as chemical reducing agent and dopant. For the first time, a DES of choline chloride and sodium sulfide comprising cheap and safe components is introduced, and is both highly effective and reusable as a reducing agent for the production of SN-rGO. The DES is utilized as a solvent as well as reducing agent and dopant to generate SN-rGO. This DES is highly efficient in removing oxygen functionalities from GO and for subsequent sulfur and nitrogen functionalization for high energy-storage efficiency. The reduction ability of this DES is confirmed with five consecutive cycles, which adds to its sustainability and recyclability in the development of energy-storage devices. SN-rGO exhibits a high specific capacitance of 509 F g-1 at 1 A g-1 , which corresponds to high energy and power densities of 57.3 Wh kg-1 and 1804.7 W kg-1 , respectively. This simple and green method for direct reduction of GO with sulfur and nitrogen functionalization on the graphene surface can provide cost-effective bulk production of a nanocarbon template for energy storage applications.

Direct TEM observation of the ``acanthite α-Ag2S-argentite β-Ag2S'' phase transition in a silver sulfide nanoparticle

Abstract: For the first time, the α-Ag2S (acanthite)–β-Ag2S (argentite) phase transition in a single silver sulfide nanoparticle has been observed in situ using a high-resolution transmission electron microscopy method in real time. Colloid solutions of Ag2S nanoparticles and nanostructured powders of silver sulfide have been synthesized by one-stage chemical bath deposition from an aqueous solution of silver nitrate, sodium sulfide and sodium citrate. Ag2S nanoparticles were heated to different temperatures directly in an electronic microscope by regulating the energy of the electron beam. This allowed observation of the transition of acanthite into argentite and the reversible transition of argentite into acanthite in real time, and this phase transition to be filmed. Temperature dependence of the lattice constant aarg of argentite β-Ag2S in the temperature range 448–723 K is established by in situ high-temperature X-ray diffraction. The orientation relationships between the monoclinic acanthite α-Ag2S and the body-centered cubic argentite β-Ag2S are determined. It is shown that the possible distances between silver atoms in cubic argentite, in contrast to those in acanthite, are too small for the positions of the metal sublattice to be occupied by Ag atoms with a probability equal to 1.

Removal of sulfide-bound copper from white wine by membrane filtration

Abstract: Background and Aims Sulfide‐bound copper (Cu) in wine may act as a potential source of hydrogen sulfide The aim of this study was to understand how the white wine matrix can influence the filterability of sulfide‐bound Cu Methods and Results Sulfide‐bound Cu was formed in situ with addition of copper(II) sulfate and sodium sulfide to white wine and model wines The amount of subsequent Cu passing through membrane filters was measured by flame atomic absorption spectroscopy or inductively coupled plasma with optical emission spectroscopy Nanoparticle tracking analysis was utilised to measure the size of particles generated after copper(II) and sulfide addition The majority of the particles were around or below 02 μm, and polyethersulfone and nylon membranes remove up to 40–90% of sulfide‐bound Cu from white wine The regenerated cellulose, Teflon and glass fibre membranes removed minimal sulfide‐bound Cu Conclusions Membrane filtration removed sulfide‐bound Cu by adsorption rather than by particle size discrimination Polysaccharides and proteins were the components of white wine that most inhibited adsorption Significance of the Study The addition of copper(II) to wine with hydrogen sulfide results in products that cannot be removed by filtration on the basis of their particle size but instead may be partly removed by adsorption onto membrane filters to an extent impacted by the wine composition and the filtration medium

Electrocatalytic Water Splitting through the Ni x S y Self-Grown Superstructures Obtained via a Wet Chemical Sulfurization Process.

Abstract: We report water-splitting application of chemically stable self-grown nickel sulfide (Ni x S y ) electrocatalysts of different nanostructures including rods, flakes, buds, petals, etc., synthesized by a hydrothermal method on a three-dimensional Ni foam (NiF) in the presence of different sulfur-ion precursors, e.g., thioacetamide, sodium thiosulfate, thiourea, and sodium sulfide. The S2- ions are produced after decomposition from respective sulfur precursors, which, in general, react with oxidized Ni2+ ions from the NiF at optimized temperatures and pressures, forming the Ni x S y superstructures. These Ni x S y electrocatalysts are initially screened for their structure, morphology, phase purity, porosity, and binding energy by means of various sophisticated instrumentation technologies. The as-obtained Ni x S y electrocatalyst from sodium thiosulfate endows an overpotential of 200 mV. The oxygen evolution overpotential results of Ni x S y electrocatalysts are comparable or superior to those reported previously for other self-grown Ni x S y superstructure morphologies.

Characterization and chemical fixation of stainless steel pickling residue using sodium sulfide hydrate.

Abstract: The stainless steel pickling residue (SSPR) produced from the stainless steel industries in China contains large amounts of heavy metals such as chromium (Cr) and nickel (Ni). The study found that the hexavalent chromium Cr (VI) was the primary contributor to the leaching of Cr in the toxicity character leaching test. A chemical fixation with sodium sulfide was used to treat the SSPR, and the response surface methodology (RSM) was employed to optimize the process. The results revealed that the sodium sulfide dose and curing time had significant effects on the fixation of Cr. The higher was the sodium sulfide dose, and the longer the curing time, the lower the leaching concentration of Cr would be. The water addition amount had insignificant effect when it was higher than 70%. A dose of 1.2% sodium sulfide on dry mass basis, a water addition of 90–100%, and a curing time of longer than 10 days in the open air could reduce the leaching of Cr to below the beneficial use threshold. The low chemical dose and simple procedures established in this study make this treatment method cost-effective for rendering the SSPR into a nonhazardous and useful material.

Effect of additives on stabilization and inhibition of mercury re-emission in simulated desulphurization slurry

Abstract: The introduction of additives into desulfurization slurry may inhibit the mercury re-emission from slurry and improve the stabilization of mercury in slurry. In this paper, the effect of common additives, such as sodium sulfide (Na2S), 2,4,6-trimercaptotriazine trisodium (TMT-18), sodium dithiocarbamate (DTCR-2) and Fenton reagent, on mercury distribution in gas–liquid–solid phase was investigated under typical operating conditions. Meanwhile, the effect of different additive dosages on the inhibition performance of mercury re-emission was studied. Furthermore, the inhibition mechanisms of different additives were also discussed. The experimental results showed that Na2S, TMT-18, DTCR-2 and Fenton reagent could inhibit the mercury re-emission from desulfurization slurry and some mercury that might reemit into the gas phase before would be restrained in the solid phase. For additives such as Na2S, TMT-18 and DTCR-2, with the increase in additive dosages, the inhibition performances of mercury re-emission were improved, but the enhancing effects tended to level off. More mercury could be restrained in the solid phase by forming HgS, Hg-TMT and Hg-DTCR. However, for additives such as Fenton reagent, the inhibition performance of mercury re-emission was first increased and then decreased with the proportion of Fe2+ and H2O2 in Fenton reagent increasing. There existed an optimal proportion. The oxygenated free radical generated by Fenton reagent with Fe2+ as catalysis was the main reason for the inhibition of mercury re-emission, and more mercury would be oxidized and then restrained in solid phase due to the formation of HgSO4 and Fe(OH)3.

Convenient one-pot access to 2H-3-nitrothiochromenes from 2-bromobenzaldehydes, sodium sulfide and β-nitrostyrenes.

Abstract: An efficient synthesis of 2H-3-nitrothiochromenes via a cascade reaction was established. Starting from commercially available o-bromobenzaldehydes and β-nitrostyrenes with sodium sulfide nonahydrate as an inexpensive sulfur source, various substituted thiochromenes were synthesized with high functional group tolerance without any added transition metal catalyst or additive.

The comparison of acid and enzymatic hydrolysis of pulp obtained from poplar wood (Populus sp.) by the Kraft method.

Abstract: This paper compares the acid and enzymatic hydrolysis in relation to bioethanol production. The pulp obtained from wood of the fast-growing poplar species (Populus deltoides x maximowiczii and Populus trichocarpa Torr. & A. Gray ex Hook) was used as a feedstock. The delignification process by the Kraft method was carried out with 19% and 26% of active alkali (NaOH and Na2S). The obtained sugars (xylose and glucose) were analyzed by a high-performance liquid chromatography. The results concluded that the enzymatic hydrolysis process is better than acid hydrolysis because a higher content of sugars (especially xylose) was obtained. Additionally, after the acid and enzymatic hydrolysis process from Populus trichocarpa pulp, more sugars were obtained than from the pulp of Populus deltoides × maximowiczii. The Kraft pulp from the wood of fast-growing poplar species is a good raw material for the production of glucose. However, in order to obtain a higher xylose content and finally increase the profitability of bioethanol production, a new method should be developed, or the Kraft method should be optimized.

Preparation method of cobalt-based bimetallic sulfide negative electrode material and application thereof

Abstract: The invention discloses a preparation method of a cobalt-based bimetallic sulfide negative electrode material (M-Co-S, M = Ni, Fe, Mo, Bi, Zn) and application of the cobalt-based bimetallic sulfide negative electrode material in a water system supercapacitor. Foamed nickel with graphene on the surface is used as a substrate, cobalt salt is used as a cobalt source, M salt is used as an M source, ammonium fluoride and hexamethyltetramine are used as precipitators, sodium sulfide is used as a vulcanizing agent, an M-Co-S film is obtained through a two-step hydrothermal method, and the M-Co-S is uniformly coated on the surface of the foamed nickel substrate with the graphene. The prepared M-Co-S material is assembled into a three-electrode system, electrochemical performance evaluation is conducted in a 1M KOH electrolyte, the maximum specific capacitance of the M-Co-S material is up to 2.6 F/cm (1625 F/g) and higher than that of common negative electrode materials, and the M-Co-S is asupercapacitor negative electrode material with great application prospects.

Preparation of [C60]fullerene nanowhisker–cadmium sulfide nanoparticle composite and its photocatalytic activity for degradation of rhodamine B

Abstract: Cadmium sulfide (CdS) nanoparticles were synthesized from cadmium sulfate (CdSO4), sodium hydroxide (NaOH), and sodium sulfide (Na2S) dissolved into distilled water, and the resulting solut...

Liquid-Phase Synthesis of Silver Sulfide Nanoparticles in Supersaturated Aqueous Solutions

Abstract: Silver sulfide powders and colloidal solutions were synthesized by chemical deposition from aqueous solutions of silver nitrate and sodium sulfide in the presence of sodium citrate as a stabilizing agent. X‑ray diffraction, electronic microscopy, the Brunauer–Emmett–Teller method, and dynamic light scattering were used to determine nanoparticle sizes in the deposited powders and colloidal solutions. The varying reagent concentrations in the reaction mixture provided nanopowders with average particle sizes ranging from ~1000 to ~40–50 nm. Silver sulfide nanoparticles in colloidal solutions have sizes of 15–20 nm. A qualitative correlation is found between the silver sulfide particle size and the supersaturation of the solutions used in the synthesis.